Purpose of Review

Regeneration of liquid desiccant solutions is critical for the liquid desiccant air conditioning (LDAC) process. In most LDAC systems, the weak desiccant solution is regenerated using the energy-intensive thermal evaporation method which suffers from desiccant carry-over. Recently, membrane processes have gained increasing interest as a promising method for liquid desiccant solution regeneration. This paper provides a comprehensive review on the applications of membrane processes for regeneration of liquid desiccant solutions. Fundamental knowledge, working principles, and the applications of four key membrane processes (e.g., reverse osmosis (RO), forward osmosis (FO), electrodialysis (ED), and membrane distillation (MD)) are discussed to shed light on their feasibility for liquid desiccant solution regeneration and the associated challenges.

Recent Findings

RO is effective at preventing desiccant carry-over; however, current RO membranes are not compatible with hypersaline liquid desiccant solutions. FO deploys a concentrated draw solution to overcome the high osmotic pressure of liquid desiccant solutions; hence, it is feasible for their regeneration despite the issues with internal/external concentration polarization and reverse salt flux. ED has proven its technical feasibility for liquid desiccant solution regeneration; nevertheless, more research into the process energy efficiency and the recycling of spent solution are recommended. Finally, as a thermally driven process, MD is capable of regenerating liquid desiccant solutions, but it is adversely affected by the polarization effects associated with the hypersalinity of the solutions.

Summary

Extensive studies are required to realize the applications of membrane processes for the regeneration of liquid desiccant solutions used for LDAC systems.

中文翻译：

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用于空调的液体干燥剂溶液再生的膜工艺

审查目的

液体干燥剂溶液的再生对于液体干燥剂空调（LDAC）过程至关重要。在大多数LDAC系统中，使用耗能大的热蒸发方法来再生弱干燥剂溶液，该方法会受到干燥剂残留的影响。近来，膜工艺作为液体干燥剂溶液再生的一种有前途的方法越来越引起人们的兴趣。本文对膜工艺在液体干燥剂溶液再生中的应用进行了全面综述。讨论了基础知识，工作原理以及四个关键膜工艺（例如，反渗透（RO），正向渗透（FO），电渗析（ED）和膜蒸馏（MD））的应用，以阐明它们的可行性液体干燥剂溶液的再生及相关挑战。

最近的发现

RO可以有效防止干燥剂残留。但是，目前的反渗透膜与高盐液体干燥剂溶液不兼容。FO部署了集中抽水解决方案，以克服液体干燥剂溶液的高渗透压；因此，尽管存在内部/外部浓度极化和反向盐通量的问题，它们的再生仍是可行的。ED证明了其在液体干燥剂溶液再生中的技术可行性；但是，建议对过程能效和废溶液的回收进行更多研究。最后，作为热驱动过程，MD能够再生液体干燥剂溶液，但是它受到与溶液过高盐度相关的极化效应的不利影响。

概要

需要进行广泛的研究以实现膜工艺在LDAC系统中使用的液体干燥剂溶液再生方面的应用。